Initial import of modified Linux 2.6.28 tree

Original upstream URL:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y

1 files changed, 1718 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
new file mode 100644
index 0000000..8f753e5
--- /dev/null
+++ b/kernel/fork.c
@@ -0,0 +1,1718 @@
+/*
+ *  linux/kernel/fork.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+/*
+ *  'fork.c' contains the help-routines for the 'fork' system call
+ * (see also entry.S and others).
+ * Fork is rather simple, once you get the hang of it, but the memory
+ * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
+ */
+
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/unistd.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/completion.h>
+#include <linux/mnt_namespace.h>
+#include <linux/personality.h>
+#include <linux/mempolicy.h>
+#include <linux/sem.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/iocontext.h>
+#include <linux/key.h>
+#include <linux/binfmts.h>
+#include <linux/mman.h>
+#include <linux/mmu_notifier.h>
+#include <linux/fs.h>
+#include <linux/nsproxy.h>
+#include <linux/capability.h>
+#include <linux/cpu.h>
+#include <linux/cgroup.h>
+#include <linux/security.h>
+#include <linux/hugetlb.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/jiffies.h>
+#include <linux/tracehook.h>
+#include <linux/futex.h>
+#include <linux/compat.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/rcupdate.h>
+#include <linux/ptrace.h>
+#include <linux/mount.h>
+#include <linux/audit.h>
+#include <linux/memcontrol.h>
+#include <linux/profile.h>
+#include <linux/rmap.h>
+#include <linux/acct.h>
+#include <linux/tsacct_kern.h>
+#include <linux/cn_proc.h>
+#include <linux/freezer.h>
+#include <linux/delayacct.h>
+#include <linux/taskstats_kern.h>
+#include <linux/random.h>
+#include <linux/tty.h>
+#include <linux/proc_fs.h>
+#include <linux/blkdev.h>
+#include <trace/sched.h>
+
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+/*
+ * Protected counters by write_lock_irq(&tasklist_lock)
+ */
+unsigned long total_forks;	/* Handle normal Linux uptimes. */
+int nr_threads; 		/* The idle threads do not count.. */
+
+int max_threads;		/* tunable limit on nr_threads */
+
+DEFINE_PER_CPU(unsigned long, process_counts) = 0;
+
+__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
+
+int nr_processes(void)
+{
+	int cpu;
+	int total = 0;
+
+	for_each_online_cpu(cpu)
+		total += per_cpu(process_counts, cpu);
+
+	return total;
+}
+
+#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
+# define alloc_task_struct()	kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
+# define free_task_struct(tsk)	kmem_cache_free(task_struct_cachep, (tsk))
+static struct kmem_cache *task_struct_cachep;
+#endif
+
+#ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
+static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)
+{
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	gfp_t mask = GFP_KERNEL | __GFP_ZERO;
+#else
+	gfp_t mask = GFP_KERNEL;
+#endif
+	return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER);
+}
+
+static inline void free_thread_info(struct thread_info *ti)
+{
+	free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
+}
+#endif
+
+/* SLAB cache for signal_struct structures (tsk->signal) */
+static struct kmem_cache *signal_cachep;
+
+/* SLAB cache for sighand_struct structures (tsk->sighand) */
+struct kmem_cache *sighand_cachep;
+
+/* SLAB cache for files_struct structures (tsk->files) */
+struct kmem_cache *files_cachep;
+
+/* SLAB cache for fs_struct structures (tsk->fs) */
+struct kmem_cache *fs_cachep;
+
+/* SLAB cache for vm_area_struct structures */
+struct kmem_cache *vm_area_cachep;
+
+/* SLAB cache for mm_struct structures (tsk->mm) */
+static struct kmem_cache *mm_cachep;
+
+void free_task(struct task_struct *tsk)
+{
+	prop_local_destroy_single(&tsk->dirties);
+	free_thread_info(tsk->stack);
+	rt_mutex_debug_task_free(tsk);
+	free_task_struct(tsk);
+}
+EXPORT_SYMBOL(free_task);
+
+void __put_task_struct(struct task_struct *tsk)
+{
+	WARN_ON(!tsk->exit_state);
+	WARN_ON(atomic_read(&tsk->usage));
+	WARN_ON(tsk == current);
+
+	security_task_free(tsk);
+	free_uid(tsk->user);
+	put_group_info(tsk->group_info);
+	delayacct_tsk_free(tsk);
+
+	if (!profile_handoff_task(tsk))
+		free_task(tsk);
+}
+
+/*
+ * macro override instead of weak attribute alias, to workaround
+ * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
+ */
+#ifndef arch_task_cache_init
+#define arch_task_cache_init()
+#endif
+
+void __init fork_init(unsigned long mempages)
+{
+#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
+#ifndef ARCH_MIN_TASKALIGN
+#define ARCH_MIN_TASKALIGN	L1_CACHE_BYTES
+#endif
+	/* create a slab on which task_structs can be allocated */
+	task_struct_cachep =
+		kmem_cache_create("task_struct", sizeof(struct task_struct),
+			ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL);
+#endif
+
+	/* do the arch specific task caches init */
+	arch_task_cache_init();
+
+	/*
+	 * The default maximum number of threads is set to a safe
+	 * value: the thread structures can take up at most half
+	 * of memory.
+	 */
+	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
+
+	/*
+	 * we need to allow at least 20 threads to boot a system
+	 */
+	if(max_threads < 20)
+		max_threads = 20;
+
+	init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
+	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
+	init_task.signal->rlim[RLIMIT_SIGPENDING] =
+		init_task.signal->rlim[RLIMIT_NPROC];
+}
+
+int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
+					       struct task_struct *src)
+{
+	*dst = *src;
+	return 0;
+}
+
+static struct task_struct *dup_task_struct(struct task_struct *orig)
+{
+	struct task_struct *tsk;
+	struct thread_info *ti;
+	int err;
+
+	prepare_to_copy(orig);
+
+	tsk = alloc_task_struct();
+	if (!tsk)
+		return NULL;
+
+	ti = alloc_thread_info(tsk);
+	if (!ti) {
+		free_task_struct(tsk);
+		return NULL;
+	}
+
+ 	err = arch_dup_task_struct(tsk, orig);
+	if (err)
+		goto out;
+
+	tsk->stack = ti;
+
+	err = prop_local_init_single(&tsk->dirties);
+	if (err)
+		goto out;
+
+	setup_thread_stack(tsk, orig);
+
+#ifdef CONFIG_CC_STACKPROTECTOR
+	tsk->stack_canary = get_random_int();
+#endif
+
+	/* One for us, one for whoever does the "release_task()" (usually parent) */
+	atomic_set(&tsk->usage,2);
+	atomic_set(&tsk->fs_excl, 0);
+#ifdef CONFIG_BLK_DEV_IO_TRACE
+	tsk->btrace_seq = 0;
+#endif
+	tsk->splice_pipe = NULL;
+	return tsk;
+
+out:
+	free_thread_info(ti);
+	free_task_struct(tsk);
+	return NULL;
+}
+
+#ifdef CONFIG_MMU
+static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+	struct vm_area_struct *mpnt, *tmp, **pprev;
+	struct rb_node **rb_link, *rb_parent;
+	int retval;
+	unsigned long charge;
+	struct mempolicy *pol;
+
+	down_write(&oldmm->mmap_sem);
+	flush_cache_dup_mm(oldmm);
+	/*
+	 * Not linked in yet - no deadlock potential:
+	 */
+	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
+
+	mm->locked_vm = 0;
+	mm->mmap = NULL;
+	mm->mmap_cache = NULL;
+	mm->free_area_cache = oldmm->mmap_base;
+	mm->cached_hole_size = ~0UL;
+	mm->map_count = 0;
+	cpus_clear(mm->cpu_vm_mask);
+	mm->mm_rb = RB_ROOT;
+	rb_link = &mm->mm_rb.rb_node;
+	rb_parent = NULL;
+	pprev = &mm->mmap;
+
+	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
+		struct file *file;
+
+		if (mpnt->vm_flags & VM_DONTCOPY) {
+			long pages = vma_pages(mpnt);
+			mm->total_vm -= pages;
+			vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
+								-pages);
+			continue;
+		}
+		charge = 0;
+		if (mpnt->vm_flags & VM_ACCOUNT) {
+			unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
+			if (security_vm_enough_memory(len))
+				goto fail_nomem;
+			charge = len;
+		}
+		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+		if (!tmp)
+			goto fail_nomem;
+		*tmp = *mpnt;
+		pol = mpol_dup(vma_policy(mpnt));
+		retval = PTR_ERR(pol);
+		if (IS_ERR(pol))
+			goto fail_nomem_policy;
+		vma_set_policy(tmp, pol);
+		tmp->vm_flags &= ~VM_LOCKED;
+		tmp->vm_mm = mm;
+		tmp->vm_next = NULL;
+		anon_vma_link(tmp);
+		file = tmp->vm_file;
+		if (file) {
+			struct inode *inode = file->f_path.dentry->d_inode;
+			struct address_space *mapping = file->f_mapping;
+
+			get_file(file);
+			if (tmp->vm_flags & VM_DENYWRITE)
+				atomic_dec(&inode->i_writecount);
+			spin_lock(&mapping->i_mmap_lock);
+			if (tmp->vm_flags & VM_SHARED)
+				mapping->i_mmap_writable++;
+			tmp->vm_truncate_count = mpnt->vm_truncate_count;
+			flush_dcache_mmap_lock(mapping);
+			/* insert tmp into the share list, just after mpnt */
+			vma_prio_tree_add(tmp, mpnt);
+			flush_dcache_mmap_unlock(mapping);
+			spin_unlock(&mapping->i_mmap_lock);
+		}
+
+		/*
+		 * Clear hugetlb-related page reserves for children. This only
+		 * affects MAP_PRIVATE mappings. Faults generated by the child
+		 * are not guaranteed to succeed, even if read-only
+		 */
+		if (is_vm_hugetlb_page(tmp))
+			reset_vma_resv_huge_pages(tmp);
+
+		/*
+		 * Link in the new vma and copy the page table entries.
+		 */
+		*pprev = tmp;
+		pprev = &tmp->vm_next;
+
+		__vma_link_rb(mm, tmp, rb_link, rb_parent);
+		rb_link = &tmp->vm_rb.rb_right;
+		rb_parent = &tmp->vm_rb;
+
+		mm->map_count++;
+		retval = copy_page_range(mm, oldmm, mpnt);
+
+		if (tmp->vm_ops && tmp->vm_ops->open)
+			tmp->vm_ops->open(tmp);
+
+		if (retval)
+			goto out;
+	}
+	/* a new mm has just been created */
+	arch_dup_mmap(oldmm, mm);
+	retval = 0;
+out:
+	up_write(&mm->mmap_sem);
+	flush_tlb_mm(oldmm);
+	up_write(&oldmm->mmap_sem);
+	return retval;
+fail_nomem_policy:
+	kmem_cache_free(vm_area_cachep, tmp);
+fail_nomem:
+	retval = -ENOMEM;
+	vm_unacct_memory(charge);
+	goto out;
+}
+
+static inline int mm_alloc_pgd(struct mm_struct * mm)
+{
+	mm->pgd = pgd_alloc(mm);
+	if (unlikely(!mm->pgd))
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void mm_free_pgd(struct mm_struct * mm)
+{
+	pgd_free(mm, mm->pgd);
+}
+#else
+#define dup_mmap(mm, oldmm)	(0)
+#define mm_alloc_pgd(mm)	(0)
+#define mm_free_pgd(mm)
+#endif /* CONFIG_MMU */
+
+__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
+
+#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
+#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))
+
+#include <linux/init_task.h>
+
+static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
+{
+	atomic_set(&mm->mm_users, 1);
+	atomic_set(&mm->mm_count, 1);
+	init_rwsem(&mm->mmap_sem);
+	INIT_LIST_HEAD(&mm->mmlist);
+	mm->flags = (current->mm) ? current->mm->flags
+				  : MMF_DUMP_FILTER_DEFAULT;
+	mm->core_state = NULL;
+	mm->nr_ptes = 0;
+	set_mm_counter(mm, file_rss, 0);
+	set_mm_counter(mm, anon_rss, 0);
+	spin_lock_init(&mm->page_table_lock);
+	rwlock_init(&mm->ioctx_list_lock);
+	mm->ioctx_list = NULL;
+	mm->free_area_cache = TASK_UNMAPPED_BASE;
+	mm->cached_hole_size = ~0UL;
+	mm_init_owner(mm, p);
+
+	if (likely(!mm_alloc_pgd(mm))) {
+		mm->def_flags = 0;
+		mmu_notifier_mm_init(mm);
+		return mm;
+	}
+
+	free_mm(mm);
+	return NULL;
+}
+
+/*
+ * Allocate and initialize an mm_struct.
+ */
+struct mm_struct * mm_alloc(void)
+{
+	struct mm_struct * mm;
+
+	mm = allocate_mm();
+	if (mm) {
+		memset(mm, 0, sizeof(*mm));
+		mm = mm_init(mm, current);
+	}
+	return mm;
+}
+
+/*
+ * Called when the last reference to the mm
+ * is dropped: either by a lazy thread or by
+ * mmput. Free the page directory and the mm.
+ */
+void __mmdrop(struct mm_struct *mm)
+{
+	BUG_ON(mm == &init_mm);
+	mm_free_pgd(mm);
+	destroy_context(mm);
+	mmu_notifier_mm_destroy(mm);
+	free_mm(mm);
+}
+EXPORT_SYMBOL_GPL(__mmdrop);
+
+/*
+ * Decrement the use count and release all resources for an mm.
+ */
+void mmput(struct mm_struct *mm)
+{
+	might_sleep();
+
+	if (atomic_dec_and_test(&mm->mm_users)) {
+		exit_aio(mm);
+		exit_mmap(mm);
+		set_mm_exe_file(mm, NULL);
+		if (!list_empty(&mm->mmlist)) {
+			spin_lock(&mmlist_lock);
+			list_del(&mm->mmlist);
+			spin_unlock(&mmlist_lock);
+		}
+		put_swap_token(mm);
+		mmdrop(mm);
+	}
+}
+EXPORT_SYMBOL_GPL(mmput);
+
+/**
+ * get_task_mm - acquire a reference to the task's mm
+ *
+ * Returns %NULL if the task has no mm.  Checks PF_KTHREAD (meaning
+ * this kernel workthread has transiently adopted a user mm with use_mm,
+ * to do its AIO) is not set and if so returns a reference to it, after
+ * bumping up the use count.  User must release the mm via mmput()
+ * after use.  Typically used by /proc and ptrace.
+ */
+struct mm_struct *get_task_mm(struct task_struct *task)
+{
+	struct mm_struct *mm;
+
+	task_lock(task);
+	mm = task->mm;
+	if (mm) {
+		if (task->flags & PF_KTHREAD)
+			mm = NULL;
+		else
+			atomic_inc(&mm->mm_users);
+	}
+	task_unlock(task);
+	return mm;
+}
+EXPORT_SYMBOL_GPL(get_task_mm);
+
+/* Please note the differences between mmput and mm_release.
+ * mmput is called whenever we stop holding onto a mm_struct,
+ * error success whatever.
+ *
+ * mm_release is called after a mm_struct has been removed
+ * from the current process.
+ *
+ * This difference is important for error handling, when we
+ * only half set up a mm_struct for a new process and need to restore
+ * the old one.  Because we mmput the new mm_struct before
+ * restoring the old one. . .
+ * Eric Biederman 10 January 1998
+ */
+void mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+	struct completion *vfork_done = tsk->vfork_done;
+
+	/* Get rid of any futexes when releasing the mm */
+#ifdef CONFIG_FUTEX
+	if (unlikely(tsk->robust_list))
+		exit_robust_list(tsk);
+#ifdef CONFIG_COMPAT
+	if (unlikely(tsk->compat_robust_list))
+		compat_exit_robust_list(tsk);
+#endif
+#endif
+
+	/* Get rid of any cached register state */
+	deactivate_mm(tsk, mm);
+
+	/* notify parent sleeping on vfork() */
+	if (vfork_done) {
+		tsk->vfork_done = NULL;
+		complete(vfork_done);
+	}
+
+	/*
+	 * If we're exiting normally, clear a user-space tid field if
+	 * requested.  We leave this alone when dying by signal, to leave
+	 * the value intact in a core dump, and to save the unnecessary
+	 * trouble otherwise.  Userland only wants this done for a sys_exit.
+	 */
+	if (tsk->clear_child_tid
+	    && !(tsk->flags & PF_SIGNALED)
+	    && atomic_read(&mm->mm_users) > 1) {
+		u32 __user * tidptr = tsk->clear_child_tid;
+		tsk->clear_child_tid = NULL;
+
+		/*
+		 * We don't check the error code - if userspace has
+		 * not set up a proper pointer then tough luck.
+		 */
+		put_user(0, tidptr);
+		sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
+	}
+}
+
+/*
+ * Allocate a new mm structure and copy contents from the
+ * mm structure of the passed in task structure.
+ */
+struct mm_struct *dup_mm(struct task_struct *tsk)
+{
+	struct mm_struct *mm, *oldmm = current->mm;
+	int err;
+
+	if (!oldmm)
+		return NULL;
+
+	mm = allocate_mm();
+	if (!mm)
+		goto fail_nomem;
+
+	memcpy(mm, oldmm, sizeof(*mm));
+
+	/* Initializing for Swap token stuff */
+	mm->token_priority = 0;
+	mm->last_interval = 0;
+
+	if (!mm_init(mm, tsk))
+		goto fail_nomem;
+
+	if (init_new_context(tsk, mm))
+		goto fail_nocontext;
+
+	dup_mm_exe_file(oldmm, mm);
+
+	err = dup_mmap(mm, oldmm);
+	if (err)
+		goto free_pt;
+
+	mm->hiwater_rss = get_mm_rss(mm);
+	mm->hiwater_vm = mm->total_vm;
+
+	return mm;
+
+free_pt:
+	mmput(mm);
+
+fail_nomem:
+	return NULL;
+
+fail_nocontext:
+	/*
+	 * If init_new_context() failed, we cannot use mmput() to free the mm
+	 * because it calls destroy_context()
+	 */
+	mm_free_pgd(mm);
+	free_mm(mm);
+	return NULL;
+}
+
+static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
+{
+	struct mm_struct * mm, *oldmm;
+	int retval;
+
+	tsk->min_flt = tsk->maj_flt = 0;
+	tsk->nvcsw = tsk->nivcsw = 0;
+
+	tsk->mm = NULL;
+	tsk->active_mm = NULL;
+
+	/*
+	 * Are we cloning a kernel thread?
+	 *
+	 * We need to steal a active VM for that..
+	 */
+	oldmm = current->mm;
+	if (!oldmm)
+		return 0;
+
+	if (clone_flags & CLONE_VM) {
+		atomic_inc(&oldmm->mm_users);
+		mm = oldmm;
+		goto good_mm;
+	}
+
+	retval = -ENOMEM;
+	mm = dup_mm(tsk);
+	if (!mm)
+		goto fail_nomem;
+
+good_mm:
+	/* Initializing for Swap token stuff */
+	mm->token_priority = 0;
+	mm->last_interval = 0;
+
+	tsk->mm = mm;
+	tsk->active_mm = mm;
+	return 0;
+
+fail_nomem:
+	return retval;
+}
+
+static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
+{
+	struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
+	/* We don't need to lock fs - think why ;-) */
+	if (fs) {
+		atomic_set(&fs->count, 1);
+		rwlock_init(&fs->lock);
+		fs->umask = old->umask;
+		read_lock(&old->lock);
+		fs->root = old->root;
+		path_get(&old->root);
+		fs->pwd = old->pwd;
+		path_get(&old->pwd);
+		read_unlock(&old->lock);
+	}
+	return fs;
+}
+
+struct fs_struct *copy_fs_struct(struct fs_struct *old)
+{
+	return __copy_fs_struct(old);
+}
+
+EXPORT_SYMBOL_GPL(copy_fs_struct);
+
+static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
+{
+	if (clone_flags & CLONE_FS) {
+		atomic_inc(&current->fs->count);
+		return 0;
+	}
+	tsk->fs = __copy_fs_struct(current->fs);
+	if (!tsk->fs)
+		return -ENOMEM;
+	return 0;
+}
+
+static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
+{
+	struct files_struct *oldf, *newf;
+	int error = 0;
+
+	/*
+	 * A background process may not have any files ...
+	 */
+	oldf = current->files;
+	if (!oldf)
+		goto out;
+
+	if (clone_flags & CLONE_FILES) {
+		atomic_inc(&oldf->count);
+		goto out;
+	}
+
+	newf = dup_fd(oldf, &error);
+	if (!newf)
+		goto out;
+
+	tsk->files = newf;
+	error = 0;
+out:
+	return error;
+}
+
+static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
+{
+#ifdef CONFIG_BLOCK
+	struct io_context *ioc = current->io_context;
+
+	if (!ioc)
+		return 0;
+	/*
+	 * Share io context with parent, if CLONE_IO is set
+	 */
+	if (clone_flags & CLONE_IO) {
+		tsk->io_context = ioc_task_link(ioc);
+		if (unlikely(!tsk->io_context))
+			return -ENOMEM;
+	} else if (ioprio_valid(ioc->ioprio)) {
+		tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
+		if (unlikely(!tsk->io_context))
+			return -ENOMEM;
+
+		tsk->io_context->ioprio = ioc->ioprio;
+	}
+#endif
+	return 0;
+}
+
+static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
+{
+	struct sighand_struct *sig;
+
+	if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
+		atomic_inc(&current->sighand->count);
+		return 0;
+	}
+	sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
+	rcu_assign_pointer(tsk->sighand, sig);
+	if (!sig)
+		return -ENOMEM;
+	atomic_set(&sig->count, 1);
+	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
+	return 0;
+}
+
+void __cleanup_sighand(struct sighand_struct *sighand)
+{
+	if (atomic_dec_and_test(&sighand->count))
+		kmem_cache_free(sighand_cachep, sighand);
+}
+
+
+/*
+ * Initialize POSIX timer handling for a thread group.
+ */
+static void posix_cpu_timers_init_group(struct signal_struct *sig)
+{
+	/* Thread group counters. */
+	thread_group_cputime_init(sig);
+
+	/* Expiration times and increments. */
+	sig->it_virt_expires = cputime_zero;
+	sig->it_virt_incr = cputime_zero;
+	sig->it_prof_expires = cputime_zero;
+	sig->it_prof_incr = cputime_zero;
+
+	/* Cached expiration times. */
+	sig->cputime_expires.prof_exp = cputime_zero;
+	sig->cputime_expires.virt_exp = cputime_zero;
+	sig->cputime_expires.sched_exp = 0;
+
+	/* The timer lists. */
+	INIT_LIST_HEAD(&sig->cpu_timers[0]);
+	INIT_LIST_HEAD(&sig->cpu_timers[1]);
+	INIT_LIST_HEAD(&sig->cpu_timers[2]);
+}
+
+static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
+{
+	struct signal_struct *sig;
+	int ret;
+
+	if (clone_flags & CLONE_THREAD) {
+		ret = thread_group_cputime_clone_thread(current);
+		if (likely(!ret)) {
+			atomic_inc(&current->signal->count);
+			atomic_inc(&current->signal->live);
+		}
+		return ret;
+	}
+	sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
+	tsk->signal = sig;
+	if (!sig)
+		return -ENOMEM;
+
+	ret = copy_thread_group_keys(tsk);
+	if (ret < 0) {
+		kmem_cache_free(signal_cachep, sig);
+		return ret;
+	}
+
+	atomic_set(&sig->count, 1);
+	atomic_set(&sig->live, 1);
+	init_waitqueue_head(&sig->wait_chldexit);
+	sig->flags = 0;
+	sig->group_exit_code = 0;
+	sig->group_exit_task = NULL;
+	sig->group_stop_count = 0;
+	sig->curr_target = tsk;
+	init_sigpending(&sig->shared_pending);
+	INIT_LIST_HEAD(&sig->posix_timers);
+
+	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	sig->it_real_incr.tv64 = 0;
+	sig->real_timer.function = it_real_fn;
+
+	sig->leader = 0;	/* session leadership doesn't inherit */
+	sig->tty_old_pgrp = NULL;
+	sig->tty = NULL;
+
+	sig->cutime = sig->cstime = cputime_zero;
+	sig->gtime = cputime_zero;
+	sig->cgtime = cputime_zero;
+	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
+	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
+	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
+	task_io_accounting_init(&sig->ioac);
+	taskstats_tgid_init(sig);
+
+	task_lock(current->group_leader);
+	memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
+	task_unlock(current->group_leader);
+
+	posix_cpu_timers_init_group(sig);
+
+	acct_init_pacct(&sig->pacct);
+
+	tty_audit_fork(sig);
+
+	return 0;
+}
+
+void __cleanup_signal(struct signal_struct *sig)
+{
+	thread_group_cputime_free(sig);
+	exit_thread_group_keys(sig);
+	tty_kref_put(sig->tty);
+	kmem_cache_free(signal_cachep, sig);
+}
+
+static void cleanup_signal(struct task_struct *tsk)
+{
+	struct signal_struct *sig = tsk->signal;
+
+	atomic_dec(&sig->live);
+
+	if (atomic_dec_and_test(&sig->count))
+		__cleanup_signal(sig);
+}
+
+static void copy_flags(unsigned long clone_flags, struct task_struct *p)
+{
+	unsigned long new_flags = p->flags;
+
+	new_flags &= ~PF_SUPERPRIV;
+	new_flags |= PF_FORKNOEXEC;
+	new_flags |= PF_STARTING;
+	p->flags = new_flags;
+	clear_freeze_flag(p);
+}
+
+SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
+{
+	current->clear_child_tid = tidptr;
+
+	return task_pid_vnr(current);
+}
+
+static void rt_mutex_init_task(struct task_struct *p)
+{
+	spin_lock_init(&p->pi_lock);
+#ifdef CONFIG_RT_MUTEXES
+	plist_head_init(&p->pi_waiters, &p->pi_lock);
+	p->pi_blocked_on = NULL;
+#endif
+}
+
+#ifdef CONFIG_MM_OWNER
+void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
+{
+	mm->owner = p;
+}
+#endif /* CONFIG_MM_OWNER */
+
+/*
+ * Initialize POSIX timer handling for a single task.
+ */
+static void posix_cpu_timers_init(struct task_struct *tsk)
+{
+	tsk->cputime_expires.prof_exp = cputime_zero;
+	tsk->cputime_expires.virt_exp = cputime_zero;
+	tsk->cputime_expires.sched_exp = 0;
+	INIT_LIST_HEAD(&tsk->cpu_timers[0]);
+	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
+	INIT_LIST_HEAD(&tsk->cpu_timers[2]);
+}
+
+/*
+ * This creates a new process as a copy of the old one,
+ * but does not actually start it yet.
+ *
+ * It copies the registers, and all the appropriate
+ * parts of the process environment (as per the clone
+ * flags). The actual kick-off is left to the caller.
+ */
+static struct task_struct *copy_process(unsigned long clone_flags,
+					unsigned long stack_start,
+					struct pt_regs *regs,
+					unsigned long stack_size,
+					int __user *child_tidptr,
+					struct pid *pid,
+					int trace)
+{
+	int retval;
+	struct task_struct *p;
+	int cgroup_callbacks_done = 0;
+
+	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * Thread groups must share signals as well, and detached threads
+	 * can only be started up within the thread group.
+	 */
+	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * Shared signal handlers imply shared VM. By way of the above,
+	 * thread groups also imply shared VM. Blocking this case allows
+	 * for various simplifications in other code.
+	 */
+	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
+		return ERR_PTR(-EINVAL);
+
+	retval = security_task_create(clone_flags);
+	if (retval)
+		goto fork_out;
+
+	retval = -ENOMEM;
+	p = dup_task_struct(current);
+	if (!p)
+		goto fork_out;
+
+	rt_mutex_init_task(p);
+
+#ifdef CONFIG_PROVE_LOCKING
+	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
+	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
+#endif
+	retval = -EAGAIN;
+	if (atomic_read(&p->user->processes) >=
+			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
+		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
+		    p->user != current->nsproxy->user_ns->root_user)
+			goto bad_fork_free;
+	}
+
+	atomic_inc(&p->user->__count);
+	atomic_inc(&p->user->processes);
+	get_group_info(p->group_info);
+
+	/*
+	 * If multiple threads are within copy_process(), then this check
+	 * triggers too late. This doesn't hurt, the check is only there
+	 * to stop root fork bombs.
+	 */
+	if (nr_threads >= max_threads)
+		goto bad_fork_cleanup_count;
+
+	if (!try_module_get(task_thread_info(p)->exec_domain->module))
+		goto bad_fork_cleanup_count;
+
+	if (p->binfmt && !try_module_get(p->binfmt->module))
+		goto bad_fork_cleanup_put_domain;
+
+	p->did_exec = 0;
+	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
+	copy_flags(clone_flags, p);
+	INIT_LIST_HEAD(&p->children);
+	INIT_LIST_HEAD(&p->sibling);
+#ifdef CONFIG_PREEMPT_RCU
+	p->rcu_read_lock_nesting = 0;
+	p->rcu_flipctr_idx = 0;
+#endif /* #ifdef CONFIG_PREEMPT_RCU */
+	p->vfork_done = NULL;
+	spin_lock_init(&p->alloc_lock);
+
+	clear_tsk_thread_flag(p, TIF_SIGPENDING);
+	init_sigpending(&p->pending);
+
+	p->utime = cputime_zero;
+	p->stime = cputime_zero;
+	p->gtime = cputime_zero;
+	p->utimescaled = cputime_zero;
+	p->stimescaled = cputime_zero;
+	p->prev_utime = cputime_zero;
+	p->prev_stime = cputime_zero;
+
+	p->default_timer_slack_ns = current->timer_slack_ns;
+
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+	p->last_switch_count = 0;
+	p->last_switch_timestamp = 0;
+#endif
+
+	task_io_accounting_init(&p->ioac);
+	acct_clear_integrals(p);
+
+	posix_cpu_timers_init(p);
+
+	p->lock_depth = -1;		/* -1 = no lock */
+	do_posix_clock_monotonic_gettime(&p->start_time);
+	p->real_start_time = p->start_time;
+	monotonic_to_bootbased(&p->real_start_time);
+#ifdef CONFIG_SECURITY
+	p->security = NULL;
+#endif
+	p->cap_bset = current->cap_bset;
+	p->io_context = NULL;
+	p->audit_context = NULL;
+	cgroup_fork(p);
+#ifdef CONFIG_NUMA
+	p->mempolicy = mpol_dup(p->mempolicy);
+ 	if (IS_ERR(p->mempolicy)) {
+ 		retval = PTR_ERR(p->mempolicy);
+ 		p->mempolicy = NULL;
+ 		goto bad_fork_cleanup_cgroup;
+ 	}
+	mpol_fix_fork_child_flag(p);
+#endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+	p->irq_events = 0;
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+	p->hardirqs_enabled = 1;
+#else
+	p->hardirqs_enabled = 0;
+#endif
+	p->hardirq_enable_ip = 0;
+	p->hardirq_enable_event = 0;
+	p->hardirq_disable_ip = _THIS_IP_;
+	p->hardirq_disable_event = 0;
+	p->softirqs_enabled = 1;
+	p->softirq_enable_ip = _THIS_IP_;
+	p->softirq_enable_event = 0;
+	p->softirq_disable_ip = 0;
+	p->softirq_disable_event = 0;
+	p->hardirq_context = 0;
+	p->softirq_context = 0;
+#endif
+#ifdef CONFIG_LOCKDEP
+	p->lockdep_depth = 0; /* no locks held yet */
+	p->curr_chain_key = 0;
+	p->lockdep_recursion = 0;
+#endif
+
+#ifdef CONFIG_DEBUG_MUTEXES
+	p->blocked_on = NULL; /* not blocked yet */
+#endif
+
+	/* Perform scheduler related setup. Assign this task to a CPU. */
+	sched_fork(p, clone_flags);
+
+	if ((retval = security_task_alloc(p)))
+		goto bad_fork_cleanup_policy;
+	if ((retval = audit_alloc(p)))
+		goto bad_fork_cleanup_security;
+	/* copy all the process information */
+	if ((retval = copy_semundo(clone_flags, p)))
+		goto bad_fork_cleanup_audit;
+	if ((retval = copy_files(clone_flags, p)))
+		goto bad_fork_cleanup_semundo;
+	if ((retval = copy_fs(clone_flags, p)))
+		goto bad_fork_cleanup_files;
+	if ((retval = copy_sighand(clone_flags, p)))
+		goto bad_fork_cleanup_fs;
+	if ((retval = copy_signal(clone_flags, p)))
+		goto bad_fork_cleanup_sighand;
+	if ((retval = copy_mm(clone_flags, p)))
+		goto bad_fork_cleanup_signal;
+	if ((retval = copy_keys(clone_flags, p)))
+		goto bad_fork_cleanup_mm;
+	if ((retval = copy_namespaces(clone_flags, p)))
+		goto bad_fork_cleanup_keys;
+	if ((retval = copy_io(clone_flags, p)))
+		goto bad_fork_cleanup_namespaces;
+	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
+	if (retval)
+		goto bad_fork_cleanup_io;
+
+	if (pid != &init_struct_pid) {
+		retval = -ENOMEM;
+		pid = alloc_pid(task_active_pid_ns(p));
+		if (!pid)
+			goto bad_fork_cleanup_io;
+
+		if (clone_flags & CLONE_NEWPID) {
+			retval = pid_ns_prepare_proc(task_active_pid_ns(p));
+			if (retval < 0)
+				goto bad_fork_free_pid;
+		}
+	}
+
+	p->pid = pid_nr(pid);
+	p->tgid = p->pid;
+	if (clone_flags & CLONE_THREAD)
+		p->tgid = current->tgid;
+
+	if (current->nsproxy != p->nsproxy) {
+		retval = ns_cgroup_clone(p, pid);
+		if (retval)
+			goto bad_fork_free_pid;
+	}
+
+	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
+	/*
+	 * Clear TID on mm_release()?
+	 */
+	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
+#ifdef CONFIG_FUTEX
+	p->robust_list = NULL;
+#ifdef CONFIG_COMPAT
+	p->compat_robust_list = NULL;
+#endif
+	INIT_LIST_HEAD(&p->pi_state_list);
+	p->pi_state_cache = NULL;
+#endif
+	/*
+	 * sigaltstack should be cleared when sharing the same VM
+	 */
+	if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
+		p->sas_ss_sp = p->sas_ss_size = 0;
+
+	/*
+	 * Syscall tracing should be turned off in the child regardless
+	 * of CLONE_PTRACE.
+	 */
+	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
+#ifdef TIF_SYSCALL_EMU
+	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
+#endif
+	clear_all_latency_tracing(p);
+
+	/* ok, now we should be set up.. */
+	p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
+	p->pdeath_signal = 0;
+	p->exit_state = 0;
+
+	/*
+	 * Ok, make it visible to the rest of the system.
+	 * We dont wake it up yet.
+	 */
+	p->group_leader = p;
+	INIT_LIST_HEAD(&p->thread_group);
+
+	/* Now that the task is set up, run cgroup callbacks if
+	 * necessary. We need to run them before the task is visible
+	 * on the tasklist. */
+	cgroup_fork_callbacks(p);
+	cgroup_callbacks_done = 1;
+
+	/* Need tasklist lock for parent etc handling! */
+	write_lock_irq(&tasklist_lock);
+
+	/*
+	 * The task hasn't been attached yet, so its cpus_allowed mask will
+	 * not be changed, nor will its assigned CPU.
+	 *
+	 * The cpus_allowed mask of the parent may have changed after it was
+	 * copied first time - so re-copy it here, then check the child's CPU
+	 * to ensure it is on a valid CPU (and if not, just force it back to
+	 * parent's CPU). This avoids alot of nasty races.
+	 */
+	p->cpus_allowed = current->cpus_allowed;
+	p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
+	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
+			!cpu_online(task_cpu(p))))
+		set_task_cpu(p, smp_processor_id());
+
+	/* CLONE_PARENT re-uses the old parent */
+	if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
+		p->real_parent = current->real_parent;
+		p->parent_exec_id = current->parent_exec_id;
+	} else {
+		p->real_parent = current;
+		p->parent_exec_id = current->self_exec_id;
+	}
+
+	spin_lock(&current->sighand->siglock);
+
+	/*
+	 * Process group and session signals need to be delivered to just the
+	 * parent before the fork or both the parent and the child after the
+	 * fork. Restart if a signal comes in before we add the new process to
+	 * it's process group.
+	 * A fatal signal pending means that current will exit, so the new
+	 * thread can't slip out of an OOM kill (or normal SIGKILL).
+ 	 */
+	recalc_sigpending();
+	if (signal_pending(current)) {
+		spin_unlock(&current->sighand->siglock);
+		write_unlock_irq(&tasklist_lock);
+		retval = -ERESTARTNOINTR;
+		goto bad_fork_free_pid;
+	}
+
+	if (clone_flags & CLONE_THREAD) {
+		p->group_leader = current->group_leader;
+		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
+	}
+
+	if (likely(p->pid)) {
+		list_add_tail(&p->sibling, &p->real_parent->children);
+		tracehook_finish_clone(p, clone_flags, trace);
+
+		if (thread_group_leader(p)) {
+			if (clone_flags & CLONE_NEWPID)
+				p->nsproxy->pid_ns->child_reaper = p;
+
+			p->signal->leader_pid = pid;
+			tty_kref_put(p->signal->tty);
+			p->signal->tty = tty_kref_get(current->signal->tty);
+			set_task_pgrp(p, task_pgrp_nr(current));
+			set_task_session(p, task_session_nr(current));
+			attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
+			attach_pid(p, PIDTYPE_SID, task_session(current));
+			list_add_tail_rcu(&p->tasks, &init_task.tasks);
+			__get_cpu_var(process_counts)++;
+		}
+		attach_pid(p, PIDTYPE_PID, pid);
+		nr_threads++;
+	}
+
+	total_forks++;
+	spin_unlock(&current->sighand->siglock);
+	write_unlock_irq(&tasklist_lock);
+	proc_fork_connector(p);
+	cgroup_post_fork(p);
+	return p;
+
+bad_fork_free_pid:
+	if (pid != &init_struct_pid)
+		free_pid(pid);
+bad_fork_cleanup_io:
+	put_io_context(p->io_context);
+bad_fork_cleanup_namespaces:
+	exit_task_namespaces(p);
+bad_fork_cleanup_keys:
+	exit_keys(p);
+bad_fork_cleanup_mm:
+	if (p->mm)
+		mmput(p->mm);
+bad_fork_cleanup_signal:
+	cleanup_signal(p);
+bad_fork_cleanup_sighand:
+	__cleanup_sighand(p->sighand);
+bad_fork_cleanup_fs:
+	exit_fs(p); /* blocking */
+bad_fork_cleanup_files:
+	exit_files(p); /* blocking */
+bad_fork_cleanup_semundo:
+	exit_sem(p);
+bad_fork_cleanup_audit:
+	audit_free(p);
+bad_fork_cleanup_security:
+	security_task_free(p);
+bad_fork_cleanup_policy:
+#ifdef CONFIG_NUMA
+	mpol_put(p->mempolicy);
+bad_fork_cleanup_cgroup:
+#endif
+	cgroup_exit(p, cgroup_callbacks_done);
+	delayacct_tsk_free(p);
+	if (p->binfmt)
+		module_put(p->binfmt->module);
+bad_fork_cleanup_put_domain:
+	module_put(task_thread_info(p)->exec_domain->module);
+bad_fork_cleanup_count:
+	put_group_info(p->group_info);
+	atomic_dec(&p->user->processes);
+	free_uid(p->user);
+bad_fork_free:
+	free_task(p);
+fork_out:
+	return ERR_PTR(retval);
+}
+
+noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
+{
+	memset(regs, 0, sizeof(struct pt_regs));
+	return regs;
+}
+
+struct task_struct * __cpuinit fork_idle(int cpu)
+{
+	struct task_struct *task;
+	struct pt_regs regs;
+
+	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
+			    &init_struct_pid, 0);
+	if (!IS_ERR(task))
+		init_idle(task, cpu);
+
+	return task;
+}
+
+/*
+ *  Ok, this is the main fork-routine.
+ *
+ * It copies the process, and if successful kick-starts
+ * it and waits for it to finish using the VM if required.
+ */
+long do_fork(unsigned long clone_flags,
+	      unsigned long stack_start,
+	      struct pt_regs *regs,
+	      unsigned long stack_size,
+	      int __user *parent_tidptr,
+	      int __user *child_tidptr)
+{
+	struct task_struct *p;
+	int trace = 0;
+	long nr;
+
+	/*
+	 * We hope to recycle these flags after 2.6.26
+	 */
+	if (unlikely(clone_flags & CLONE_STOPPED)) {
+		static int __read_mostly count = 100;
+
+		if (count > 0 && printk_ratelimit()) {
+			char comm[TASK_COMM_LEN];
+
+			count--;
+			printk(KERN_INFO "fork(): process `%s' used deprecated "
+					"clone flags 0x%lx\n",
+				get_task_comm(comm, current),
+				clone_flags & CLONE_STOPPED);
+		}
+	}
+
+	/*
+	 * When called from kernel_thread, don't do user tracing stuff.
+	 */
+	if (likely(user_mode(regs)))
+		trace = tracehook_prepare_clone(clone_flags);
+
+	p = copy_process(clone_flags, stack_start, regs, stack_size,
+			 child_tidptr, NULL, trace);
+	/*
+	 * Do this prior waking up the new thread - the thread pointer
+	 * might get invalid after that point, if the thread exits quickly.
+	 */
+	if (!IS_ERR(p)) {
+		struct completion vfork;
+
+		trace_sched_process_fork(current, p);
+
+		nr = task_pid_vnr(p);
+
+		if (clone_flags & CLONE_PARENT_SETTID)
+			put_user(nr, parent_tidptr);
+
+		if (clone_flags & CLONE_VFORK) {
+			p->vfork_done = &vfork;
+			init_completion(&vfork);
+		}
+
+		audit_finish_fork(p);
+		tracehook_report_clone(trace, regs, clone_flags, nr, p);
+
+		/*
+		 * We set PF_STARTING at creation in case tracing wants to
+		 * use this to distinguish a fully live task from one that
+		 * hasn't gotten to tracehook_report_clone() yet.  Now we
+		 * clear it and set the child going.
+		 */
+		p->flags &= ~PF_STARTING;
+
+		if (unlikely(clone_flags & CLONE_STOPPED)) {
+			/*
+			 * We'll start up with an immediate SIGSTOP.
+			 */
+			sigaddset(&p->pending.signal, SIGSTOP);
+			set_tsk_thread_flag(p, TIF_SIGPENDING);
+			__set_task_state(p, TASK_STOPPED);
+		} else {
+			wake_up_new_task(p, clone_flags);
+		}
+
+		tracehook_report_clone_complete(trace, regs,
+						clone_flags, nr, p);
+
+		if (clone_flags & CLONE_VFORK) {
+			freezer_do_not_count();
+			wait_for_completion(&vfork);
+			freezer_count();
+			tracehook_report_vfork_done(p, nr);
+		}
+	} else {
+		nr = PTR_ERR(p);
+	}
+	return nr;
+}
+
+#ifndef ARCH_MIN_MMSTRUCT_ALIGN
+#define ARCH_MIN_MMSTRUCT_ALIGN 0
+#endif
+
+static void sighand_ctor(void *data)
+{
+	struct sighand_struct *sighand = data;
+
+	spin_lock_init(&sighand->siglock);
+	init_waitqueue_head(&sighand->signalfd_wqh);
+}
+
+void __init proc_caches_init(void)
+{
+	sighand_cachep = kmem_cache_create("sighand_cache",
+			sizeof(struct sighand_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
+			sighand_ctor);
+	signal_cachep = kmem_cache_create("signal_cache",
+			sizeof(struct signal_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+	files_cachep = kmem_cache_create("files_cache",
+			sizeof(struct files_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+	fs_cachep = kmem_cache_create("fs_cache",
+			sizeof(struct fs_struct), 0,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+	vm_area_cachep = kmem_cache_create("vm_area_struct",
+			sizeof(struct vm_area_struct), 0,
+			SLAB_PANIC, NULL);
+	mm_cachep = kmem_cache_create("mm_struct",
+			sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
+			SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+}
+
+/*
+ * Check constraints on flags passed to the unshare system call and
+ * force unsharing of additional process context as appropriate.
+ */
+static void check_unshare_flags(unsigned long *flags_ptr)
+{
+	/*
+	 * If unsharing a thread from a thread group, must also
+	 * unshare vm.
+	 */
+	if (*flags_ptr & CLONE_THREAD)
+		*flags_ptr |= CLONE_VM;
+
+	/*
+	 * If unsharing vm, must also unshare signal handlers.
+	 */
+	if (*flags_ptr & CLONE_VM)
+		*flags_ptr |= CLONE_SIGHAND;
+
+	/*
+	 * If unsharing signal handlers and the task was created
+	 * using CLONE_THREAD, then must unshare the thread
+	 */
+	if ((*flags_ptr & CLONE_SIGHAND) &&
+	    (atomic_read(&current->signal->count) > 1))
+		*flags_ptr |= CLONE_THREAD;
+
+	/*
+	 * If unsharing namespace, must also unshare filesystem information.
+	 */
+	if (*flags_ptr & CLONE_NEWNS)
+		*flags_ptr |= CLONE_FS;
+}
+
+/*
+ * Unsharing of tasks created with CLONE_THREAD is not supported yet
+ */
+static int unshare_thread(unsigned long unshare_flags)
+{
+	if (unshare_flags & CLONE_THREAD)
+		return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * Unshare the filesystem structure if it is being shared
+ */
+static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
+{
+	struct fs_struct *fs = current->fs;
+
+	if ((unshare_flags & CLONE_FS) &&
+	    (fs && atomic_read(&fs->count) > 1)) {
+		*new_fsp = __copy_fs_struct(current->fs);
+		if (!*new_fsp)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/*
+ * Unsharing of sighand is not supported yet
+ */
+static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
+{
+	struct sighand_struct *sigh = current->sighand;
+
+	if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
+		return -EINVAL;
+	else
+		return 0;
+}
+
+/*
+ * Unshare vm if it is being shared
+ */
+static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
+{
+	struct mm_struct *mm = current->mm;
+
+	if ((unshare_flags & CLONE_VM) &&
+	    (mm && atomic_read(&mm->mm_users) > 1)) {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Unshare file descriptor table if it is being shared
+ */
+static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
+{
+	struct files_struct *fd = current->files;
+	int error = 0;
+
+	if ((unshare_flags & CLONE_FILES) &&
+	    (fd && atomic_read(&fd->count) > 1)) {
+		*new_fdp = dup_fd(fd, &error);
+		if (!*new_fdp)
+			return error;
+	}
+
+	return 0;
+}
+
+/*
+ * unshare allows a process to 'unshare' part of the process
+ * context which was originally shared using clone.  copy_*
+ * functions used by do_fork() cannot be used here directly
+ * because they modify an inactive task_struct that is being
+ * constructed. Here we are modifying the current, active,
+ * task_struct.
+ */
+SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
+{
+	int err = 0;
+	struct fs_struct *fs, *new_fs = NULL;
+	struct sighand_struct *new_sigh = NULL;
+	struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
+	struct files_struct *fd, *new_fd = NULL;
+	struct nsproxy *new_nsproxy = NULL;
+	int do_sysvsem = 0;
+
+	check_unshare_flags(&unshare_flags);
+
+	/* Return -EINVAL for all unsupported flags */
+	err = -EINVAL;
+	if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
+				CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
+				CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
+				CLONE_NEWNET))
+		goto bad_unshare_out;
+
+	/*
+	 * CLONE_NEWIPC must also detach from the undolist: after switching
+	 * to a new ipc namespace, the semaphore arrays from the old
+	 * namespace are unreachable.
+	 */
+	if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
+		do_sysvsem = 1;
+	if ((err = unshare_thread(unshare_flags)))
+		goto bad_unshare_out;
+	if ((err = unshare_fs(unshare_flags, &new_fs)))
+		goto bad_unshare_cleanup_thread;
+	if ((err = unshare_sighand(unshare_flags, &new_sigh)))
+		goto bad_unshare_cleanup_fs;
+	if ((err = unshare_vm(unshare_flags, &new_mm)))
+		goto bad_unshare_cleanup_sigh;
+	if ((err = unshare_fd(unshare_flags, &new_fd)))
+		goto bad_unshare_cleanup_vm;
+	if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
+			new_fs)))
+		goto bad_unshare_cleanup_fd;
+
+	if (new_fs ||  new_mm || new_fd || do_sysvsem || new_nsproxy) {
+		if (do_sysvsem) {
+			/*
+			 * CLONE_SYSVSEM is equivalent to sys_exit().
+			 */
+			exit_sem(current);
+		}
+
+		if (new_nsproxy) {
+			switch_task_namespaces(current, new_nsproxy);
+			new_nsproxy = NULL;
+		}
+
+		task_lock(current);
+
+		if (new_fs) {
+			fs = current->fs;
+			current->fs = new_fs;
+			new_fs = fs;
+		}
+
+		if (new_mm) {
+			mm = current->mm;
+			active_mm = current->active_mm;
+			current->mm = new_mm;
+			current->active_mm = new_mm;
+			activate_mm(active_mm, new_mm);
+			new_mm = mm;
+		}
+
+		if (new_fd) {
+			fd = current->files;
+			current->files = new_fd;
+			new_fd = fd;
+		}
+
+		task_unlock(current);
+	}
+
+	if (new_nsproxy)
+		put_nsproxy(new_nsproxy);
+
+bad_unshare_cleanup_fd:
+	if (new_fd)
+		put_files_struct(new_fd);
+
+bad_unshare_cleanup_vm:
+	if (new_mm)
+		mmput(new_mm);
+
+bad_unshare_cleanup_sigh:
+	if (new_sigh)
+		if (atomic_dec_and_test(&new_sigh->count))
+			kmem_cache_free(sighand_cachep, new_sigh);
+
+bad_unshare_cleanup_fs:
+	if (new_fs)
+		put_fs_struct(new_fs);
+
+bad_unshare_cleanup_thread:
+bad_unshare_out:
+	return err;
+}
+
+/*
+ *	Helper to unshare the files of the current task.
+ *	We don't want to expose copy_files internals to
+ *	the exec layer of the kernel.
+ */
+
+int unshare_files(struct files_struct **displaced)
+{
+	struct task_struct *task = current;
+	struct files_struct *copy = NULL;
+	int error;
+
+	error = unshare_fd(CLONE_FILES, &copy);
+	if (error || !copy) {
+		*displaced = NULL;
+		return error;
+	}
+	*displaced = task->files;
+	task_lock(task);
+	task->files = copy;
+	task_unlock(task);
+	return 0;
+}